The present invention relates to a thermal transfer type recording apparatus which feeds a recording sheet and an ink sheet in layers and causes a thermal head to selectively heat the ink sheet to transfer ink from the former to the latter for thereby producing a desired image thereon. More particularly, the present invention relates to a sheet separation system for separating the recording sheet from the ink sheet after the ink transfer.
In a recorder of the type described, a recording sheet is fed to a thermal head with its image forming surface held in contact with an ink surface of an ink sheet. The thermal head, in response to input video information, transfers ink from the ink sheet to the recording sheet by application of heat. The recording sheet carrying the information thereon is separated from the ink sheet in a predetermined position. A problem encountered with such a recorder is that it is difficult to smoothly separate the processed recording sheet from the ink sheet. The difficulty is significant when a leading end portion of the recording sheet is smeared throughly black or, if not throughly, occupied by images in a high density. Such an ink distribution at the leading end portion of the recording sheet makes it difficult to separate the ink sheet therefrom. This phenomenon is more enhanced when the recorder is used in hot and humid ambient conditions. Should the separation be incomplete, the recording sheet would be entrained by the ink sheet to result in sheet jams, damage to the recording sheet and other troubles.
Various sheet separation systems for a recorder of the type concerned have heretofore been proposed to solve the problem mentioned above. One of them is constructed to sharply deflect an ink sheet at a predetermined position relative to a recording sheet, while allowing the latter to advance horizontally. However, this prior art sheet separation system is not more than a passive measure which simply utilizes the physical property of sheets and, therefore, lacks in reliability.
Another and more positive prior art sheet separation system uses a pawl or like separating member to forcibly separate a recording sheet from an ink sheet. However, just as it solves the problem of poor reliability in operation, it creates another problem concerning the quality of produced images. The separating member, which abuts against the ink surface of the ink sheet at its leading end, tends to shave the ink off the sheet surface to smear unwanted areas of a recording sheet therewith.